Past elevations of land, however (and doubtless equally great subsidences) have taken place in South America since the Eocene, and the conclusion that extensive areas of land have subsided in the Indian Ocean has long been based on a somewhat similar distribution of giant tortoises in the Mascarene region.
The flora and also (though to a less degree) the fauna present not only Asian and Central African affinities, but, what is more interesting, Mascarene, South African and Antipodean-American relationships, indicating a very different distribution of land and water and necessitating other bridges of communication than now exist.
The Antipodean-American element in the Sokotran flora probably arrived via the Mascarene Islands or South Africa from a former Antarctic continent.
In common with the other Mascarene islands, it was the home of the dodo (Didus ineptus); there were also A phanapteryx, a species of rail, and a shortwinged heron (Ardea megacephala), which probably seldom flew.
The 2000fathom line approaches close to the coast except (I) in the Bay of Bengal, which it does not enter; (2) to the south-west of India along a ridge on which are the Laccadive and Maldive Islands; and (3) in the Mozambique Channel, and on a bank north and east of Madagascar, on which are the Seychelles, Mascarene Islands and other groups.